Present Dual in Line (DIP) sockets include dual beam contacts for making contact to pins extending from integrated circuits (ICs). These DIP sockets are represented by two types of connectors, namely a U-shaped dual beam connector manufactured by Robertson-Nugent and a semi-dual beam connector of Amp Corporation, which has a stationary arm mounted in opposition to a reverse-bend contact arm.
In actual practice, both of these sockets are mounted directly against the printed circuit board to which they are soldered. However, one of the major disadvantages of the mounting of standard DIP socket connectors against the printed circuit board is that soldering flux deposited over the printed circuit board prior to mounting of the connector is difficult to clean out from between the two adjacent parts. Secondly, there is no air flow between the parts or very restricted air flow which limits heat dissipation. Finally, during wave soldering, it is common that the solder flows up through the through-holes in the printed circuit board and extends over the top surface of the printed circuit board at the holes. In general this is considered to be a deleterious effect of wave soldering, and the sockets heretofore have not utilized this solder outflow to advantage.
Another major problem with standard DIP sockets is the problem of the height of the socket seating plane above the circuit board to which it is mounted. One of the major factors in the selection of a socket is that the seating plane for an integrated circuit, e.g., the top surface of the socket, should be as low to the printed circuit board as possible. Note that sockets using the U-shaped contacts and the semi-dual beam contacts have seating plane heights of approximately 0.200 inches and 0.175 inches respectively. With respect to the sockets having U-shaped contacts, since the contacts have flaired-out ends, the flairing increases the overall height of the contact, and therefore the overall height of the socket. The semi-dual beam socket has this same problem with the flairing of its stationary contact arm.
Moreover, another factor is the contact depth, or the depth at which an IC pin makes contact with the dual beams or arms within the socket of a connector. The higher the contact point, the more that the inserted pin will extend into the socket. The result is more wiping action when the pin is pulled out of the socket. It will be noted that the semi-dual beam has a relatively low contact point, which limits the amount of wiping action provided by the withdrawal of the pin from the socket.
With respect to the wiping action of the aforementioned U-shaped dual beam contact, it will be appreciated that the force applied by the opposed contact arms or beams to an inserted pin is at right angles or perpendicular to the pin. This limits the scrubbing or wiping action on both sides of the pin.
While the aforementioned socket utilizing U-shaped contacts is loaded from the bottom in a so-called bottomloaded configuration, the semi-dual beam socket is toploaded, or mounted through the top surface of the socket, leaving the top of the contact exposed without protection from a restricted socket aperture. Upon insertion, if the pins from the integrated circuit are bent, they rest on the top of the contact, instead of going through the contact. Thus electrical connection is made by virtue of the pin resting on top of the contact. Because the pin rests on top of the contact and is not sitting in the contact, good electrical joints cannot be made and fail frequently during vibration.
Further with respect to the bottomloaded U-shaped contact, when the contact is mounted from the bottom in the socket of the connector, it is important that the contact be sealed from the bottom to prevent solder contamination. A wafer seal is usually provided to prevent any solder flux from entering the contact area. However, the addition of the wafer is a time-consuming process, which makes the socket more expensive to manufacture.